On the interfacial reactions between VO2 and thin metal films

•Competitive synthesis of VO2(M1) phase that undergo MIT transition.•Thin-film metal-VO2 couples were annealed for 1 h up to 900 °C.•Solid-state interfacial reactions between VO2 and metals Co, Hf, Ni, Pd, Au and Pt.

We have investigated solid-state interfacial reactions between VO2 and the metals Co, Hf, Ni, Pd, Pt and Au to establish possible criteria for whether a metal will react with VO2 or not. Thin-film metal-VO2 couples were annealed for periods ranging from 45 to 60 min at temperatures in the range 400-900 °C, and characterized using Rutherford backscattering spectrometry and X-ray diffraction. No interfacial reactions were detected between VO2 and Co, Ni, Pd, Au and Pt, but Hf did react. Metals with a positive heat of reaction ΔH and electronegativity φ∗, as defined by Miedema, greater than 4.9 V did not react with VO2 whereas Hf with φ∗< 4.9 V and a negative ΔH did. This correlation between the heats of reaction and the Meidema electronegativity of metals offers an empirical criterion for predicting whether a metal will react with VO2 or not.